By Göran Bryntse, PhD in Paper Technology
Assistant professor in Graphic Arts Technology at Högskolan Dalarna
 

Potential electricity savings in the swedish paper industry

More efficient mechanical pulp refining  3 TWh
Better pumps    2 TWh
Better fans                       1 TWh
Better motors                     0,5 TWh
Others     0,5 TWh
   Sum  7 TWh

Motivated  consumption, 22 – 7 TWh             =  15 TWh

Increased power generation potential

Black liquor gasification   +10 TWh
Waste heat power generation                      +2 TWh
Bark incineration power   + 2 TWh

Power generated 2006:

Back-pressure turbines    5,5 TWh

Total potential    ca 20 TWh
 

Efficient thermo-mechanical pulp

Holmen and Metso is now reconstructing the TMP-plant in  printing paper mill Braviken. 
The new technology is expected to save 600 kWh/ton pulp.

There are three parts in the new technology:

1)   Pretreatment of the chips

2) Control of the pressure in the refiner

3) Combination of HC- and LC-refining
 

If this technology is introduced in all printing paper mills the total savings would be 2,25 TWh according to the Swedish Energy Authority
 
 

Efficient CTMP manufacturing

CTMP  manufacturing for board and tissue qualities only needs about 500 kWh/ton according to results in Östrand CTMP mill outside Sundsvall.

Fors board mill in Dalarna needed 2005 about 1300 kWh/ton  CTMP. Soon they are down to about 600 kWh/ton.
 

Higher rotational speed in the refiner saves energy

Andritz  delivers refiners with 2300 rpm instead of the conventional 1500 rpm technology. A reduction of more than 300 kWh/ton electric energy was observed with no change in pulp quality.
 

More efficient pumping

According to an international survey from 2001, ”Pump life cycle costs: A Guide to LCC Analysis for pumping systems”,  do pumps consume 17-20 % of all electricity produced. 30-50 % savings are possible.

Sulzer and Scanpump have recently developed more efficient pumps than before, i.e. Sulzer Enersave and Scanpump BE serries, launched 2005.
 

Frequency controlled pumps are now cheaper than ever and profitable for almost all pumps in a pulp or paper mill.

About 8 TWh are consumed yearly by pumps in the Swedish pulp and paper industry.  2 -3 TWh can be saved by introducing more efficient  technology. 
 

Energy efficient  fans

Fans in Europe consume more than 200 TWh/year electric energy. By using efficient fans with drive control  20 % of this energy can be saved.

Fans in the Swedish pulp and paper industry consumes about 2,5 TWh/year.

A new Swedish invention, the so called spiral fan, constructed in order to use the so called Archimedes Spiral Principle, saves at least 15 % of what a conventional fan consumes. Also, the fan is more quiet because it does not generate any turbulent flow. A demo version is now operating at Hallsta  newsprint mill in Sweden.
 

More efficient motors

Motors are classified in different categories. The highest efficiency class among standard motors are Eff 1. Quite a noticeable saving could be reached by using these motors consequently in the pulp and paper industry.

However, due to a Demand Side Management program of IEA, where I participated, ABB developed their motors, called ” High performance” or ”Eff 1 plus”. These motors, who won the IEA competition in the beginning of this century, has about 15 % less losses than Eff 1 –motors.

The Swedish pulp and paper industry could  save about 0,5 TWh by  consequent usage of ABBs High Performance motors.
 

Other savings

The usage of pressurized air and vacuum should be optimized in the paper industry, thus decreasing energy demand.

Aspa Mill at lake Vättern only needs about 580 kWh/ ton softwood kraft pulp. This can be compared with the KAM2 model mill, presented by the industry, ending up in 712 kWh/ton. 
One reason is that pulp washing in Aspa is performed at 5 % consistency, resulting in lower need for pumping a lot of water.

Beating energy of the pulp can be decreased substantially. Yearly about 1 TWh is consumed in Sweden while beating the pulp. 

By the so called Finebar method, allowing lower specific edge power in the beating equipment, combined with other optimized control,  about 30 % of the beating energy can be saved.

Summary

The Swedish pulp and paper industry can be completely self sufficient in energy supply. This industry as a whole thus does not need any external electricity supply from the grid.

The Swedish and the Finnish pulp and paper industry are similar to a large extent. Therefore, the Finnish pulp and paper industry, as well as the Swedish, does not need nuclear power.
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